Saint Matthew is shown writing his gospel; the angel beside him represents his divine inspiration. Saint Catherine of Alexandria wears the crown of a princess. Fragments of the wheel on which she was tortured lie at her feet. She was finally beheaded, hence the sword she carries. Saint John the Evangelist carries pen & ink at his belt. The eagle next to him symbolises the inspiration for his Book of Revelations, while the snake & chalice refer to his survival after having drunk poison. The damaged reverse shows Saint Jerome, a female martyr, Saint Gregory the Great & a kneeling donor in the cloak of a Knight of Malta. This painting once formed the left-hand shutter of an altarpiece, probably made for a church in Cologne, of which the central panel is now lost. The other shutter showing saints Mark, Barbara & Luke on the front & saints Ambrose, Cecilia & Augustine on the reverse, is in the Wallraf-Richartz Museum in Cologne. Both reverses include donors wearing the emblem of the Knights of Malta.